In recent years, it has been obvious that the propagation characteristics of electromagnetic waves are able to be controlled by periodically arranging conductor patterns having a specific structure (hereinafter, called a metamaterial). For example, a reduction in size and thickness of an antenna can be achieved by using a metamaterial.
There are a so-called right-handed system, left-handed system, and right-handed and left-handed composite system in metamaterials. Patent Document 1 discloses a technique in which among the systems, a metamaterial of the right-handed and left-handed composite system is used as an array antenna (leaky wave antenna). This technique is used to arrange a liquid crystal layer between two conductors constituting a capacitive component of a unit cell of a metamaterial. It discloses that since a variation in a voltage applied between the two conductors gives rise to a change in the dielectric constant of the liquid crystal layer, the directionality of electromagnetic waves changes as a result.